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1. Field of the Invention
This invention relates generally to automated systems for transporting materials. More particularly, this invention relates to a substrate-handling robot with a batch loader.
2. Background of the Invention
Robots are used in a variety of industrial processes. For example, robots are used to handle substrates in the electronics industry. The term xe2x80x9csubstratexe2x80x9d includes such devices as semiconductor wafers, liquid crystal displays, flat panel displays, disk drives, and the like. Substrates are commonly stored in cassettes. In the case of a semiconductor wafer, a cassette of wafers is delivered to a work area. A robotic arm is used to take a single wafer from the cassette and deliver it to a pre-aligner. Once the wafer is pre-aligned, the robotic arm delivers the wafer to a testing apparatus. When testing is completed, the wafer is returned to the original cassette or a different cassette by the robotic arm. While existing robotic arms are acceptable for individual manipulation of substrates in a cassette, they are relatively inefficient for rapidly dispatching a set of substrates from one cassette to another or for performing other types of bulk transfer operations.
Thus, it would be highly desirable to provide an improved technique for robotic-based bulk transfers of substrates. Ideally, the bulk transfer technique would be capable of transferring various numerical combinations of substrates to optimize transfer operations. The bulk transfer technique would preferably have a low-cost mechanism for determining the number of substrates being transferred at any given time and would adjust the speed of its motion accordingly. Such a device should use known materials and techniques and otherwise be compatible with existing robotic processes.
This invention relates to a substrate-handling robot with a batch loader including individual vacuum control at batch loader paddles. More particularly, the apparatus of the invention includes a substrate-handling robot with an arm drive mechanism having a first arm connected to it. A multiple substrate batch loader is connected to the first arm. The multiple substrate batch loader includes a set of vertically stacked substrate handling paddles. A control circuit is connected to the arm drive mechanism. A vacuum control system is connected to the multiple substrate batch loader and the control circuit. The vacuum control system includes a set of vacuum control valves corresponding to the set of vertically stacked substrate handling paddles. The set of vacuum control valves includes a selected vacuum control valve for a selected substrate handling paddle. A set of vacuum sensors is connected to the set of vacuum control valves. The set of vacuum sensors includes a selected vacuum sensor corresponding to the selected vacuum control valve. The selected vacuum sensor provides a substrate-absent signal when a substrate is not present at the selected substrate-handling paddle. The substrate-absent signal is processed by the control circuit, which generates a shut-valve signal that causes the selected vacuum control valve to shut.
The method of the invention includes the step of lifting a plurality of substrates from a storage site with a multiple substrate batch loader that has a set of paddles. A pressure level is measured at each paddle of the set of paddles. A valve is shut at a selected paddle of the set of paddles when a measure pressure level is above a predetermined threshold. The multiple substrate batch loader can then be moved at full speed without danger of a substrate falling, since no vacuum leak exists.
The invention provides an improved technique for robotic-based bulk transfers of substrates. The bulk transfer technique of the invention allows for the transfer of various numerical combinations of substrates to optimize transfer operations. The vacuum sensor associated with the multiple substrate batch loader facilitates a low cost assessment of the number of substrates being transferred at any given time. Based upon this information, the motion of the robot may be optimized. Advantageously, the invention utilizes known materials and techniques and is otherwise compatible with existing processes.